1Fast99GTP

I have recently bypassed the fuel pressure regulator VSV (I just learned what it was called) on my 92 SC400, is that a good idea? Most cars I have owned and built just run a vac line from a intake vacuum port directly to the fuel pressure regulator. I would love any advice on how it works what it does would be very welcomed PLEASE!

gunyvw

i found this answer in the supra forum...

"The more pressure the regulator sees the higher the fuel pressure. At idle, the engine is under vacuum so the fuel pressure is at it's lowest point. At start up, the vsv disconnects the vacuum source so the fuel pressure regulator gets air from the atmosphere, not a reference from the manifold. This allows for higher fuel pressure. The purpose is for the engine to get more fuel at start up, so it starts easier."
So if it was fouled or broken it wouldn't allow the FPR to make enough pressure to pump in fuel.

but what i want to know is in your sig you state that you have the #4 solenoid bypass... i want to know how (which method did you use to do it)... for how long you've been running it... and if there are any 'side affects' to it long term (as you have seen) excuse me for going off topic.

1Fast99GTP

No prob man and thanks for the info!!
As with the #4 solenoid bypass, I 1st tried to just unplug it on the trans and found out it did not like that way very much at all when it would shift under I would say 85% or less throttle it bogged down like it was pulling a LOT of timing or something because of the fault also under WOT it would short shift around 5400 RPM but they were nice fast firm shifts. The OD light flashing also was very annoying .SO I plugged it back in and and drove around for a day and it was back to normal smooth shifts after clearing the PCM. Next I pulled the carpet back and took off the big black cover and found the pin location for the #4 solenoid on the PCM. The wire is a pink with a black stripe. I cut it went and took it for a drive and it was amazing! Shifts with no bog and at WOT it shifts where it should firl and fast. I have had it this way for about 5 months and not one issue and I beat the **** out of my SC LOL

gunyvw

^^^ great thanks this is what i have been thinking of doing for a while but needed more feedback.
kc95sc400 i think that's the name out of Norh Carolina had a supercharged sc400 that took off like a jet. and he kinda brain child this idea.

i want to do this and put the wire's on a switch so when i want the power i can click on and off as needed will be at this next weekend.
thanks again.

oldManTan

bringing this one back, has anyone hooked it up to a switch? i wanna run some long wire to a switch in the glove box or something. my only question is, would it affect the ECU or tranny if i turned the switch while driving? or should ou turn the car off and then switch it?

Ali SC3

iTrader: (10)

you can probably do it on the fly on obd1 cars, those solenoids are triggered by that each time by the ecu, so if you disconnect it the solenoid would just turn off if it was on or vice versa.

oldManTan

cut the wire today, holy hell the car feels so awesome. just bangs through gears like it's a paddle shifter double clutch. feels great. downshifts like it should too without slipping the gears. this is an awesome mod. i probably will set the switch up and keep it off all the time, this is just too good.

t2d2

iTrader: (8)

I forget what site I found it on, but this HP/Torque chart shows how much performance potential is hidden away in Lexus' luxury cruiser presentation of the 1UZFE. That torque curve is just begging for smoking the tires off the line!

Ali SC3

iTrader: (10)

thats exactly why I always wanted a 400 to play with and manual swap so I can deliver all that power whenever wanted. that and a supercharger would obviously be involved somehow =)

t2d2

iTrader: (8)

Man, I'm envious of the guys who've done a manual swap into the SC400. That's my ultimate wish list item right there! The solenoid bypass is a huge improvement, but there's still nothing like being able to control the gearing with a stick.

oldManTan

there's def a difference. i'm loving it so far. saving up for a manual swap for next year and this car will be golden. by then i'll probably have over a quarter million miles lol

oldManTan

wired in the switch today and it works while driving. it's crazy the difference this makes. my girlfriend asked what's wrong with my car lol. feels great though!

t2d2

iTrader: (8)

Thanks for reporting back. Good to know that works!

oldManTan

i'll post a 0-60 time tonight. see if this made a difference

oldManTan

forgot to post 0-60 times

did a few rough runs just messing around with the car performance app. it's free and uses your GPS to calculate speed and 0-60 and other times.

so here's the times:
stock ECT normal - 7.78
Bypass ECT normal - 7.24

so it's a pretty big jump if the app is correct, and this is average of 2 runs for each. my ECT switch wasn't working at the time and i had bad plugs that i hadn't changed after doing a seafoam treatment. so now that i'll be off school i'll be able to do more testing and post up some more results since the car is in tip top shape.